Some dates recognized as dates, some dates not recognized. Why?

Question

Here is a list of dates:

04-22-11
12-19-11
11-04-11
12-08-11
09-27-11
09-27-11
04-01-11

When you copy this list in Excel, some of th

Answer 1

Right-click on the column header and select Format Cells, the chose Date and select the desired date format. Those that are not recognized are ambiguous, and as such not interpreted as anything but that is resolved after applying formatting to the column. Note that for me, in Excel 2002 SP3, the dates given above are automatically and correctly interpreted as dates when pasting.